A shaking table is the cleaning-stage counterpart to the primary gravity equipment covered elsewhere in this set, Knelson, Falcon, and spiral concentrators, and it is built to upgrade a rough concentrate into a clean, high-grade product rather than to process a full tailings stream from scratch. It is among the oldest gravity technologies still in routine industrial use, with the basic reciprocating-deck principle predating centrifugal concentrators by decades, and it remains standard practice today precisely because nothing else matches its selectivity at the final cleaning stage.
How does a shaking table separate particles?
A shaking table separates particles using a riffled deck that reciprocates back and forth along its length while a thin film of wash water flows across it from a feed launder at one corner. Denser particles, including gold, work their way into and along the riffles under the shake motion, while lighter gangue is carried across the deck and off the far edge by the wash water. The result, when the table is running correctly, is a series of visible bands across the deck, with the densest, highest-grade material concentrated in a narrow band near one corner.
The deck itself is mounted at a slight, adjustable tilt away from the feed side, and the reciprocating motion is asymmetric: a slow forward stroke followed by a fast return stroke. That asymmetry is what walks dense particles along the deck's riffles toward the concentrate discharge corner even while the wash water film continuously pushes lighter material across and off the deck's lower edge. Deck material also varies, with rubber and fibreglass composite decks common in modern installations for their combination of wear resistance and consistent riffle geometry over years of continuous flexing.
Riffle height decreases progressively from the feed side toward the concentrate corner, tapering to nothing by the discharge point, which lets the table transition gradually from bulk separation near the feed to fine final cleaning near the discharge. That taper is a deliberate design feature rather than wear, and it is part of why a table achieves such sharp selectivity compared with a device that relies on riffles of uniform height throughout.
Why are tables used as a cleaning stage rather than primary recovery on tailings?
Tables process a relatively small volume per unit of deck area compared with a centrifugal concentrator or a spiral, which makes them impractical as the first gravity stage on a full-scale tailings flowsheet where throughput is measured in tonnes per hour. What a table does exceptionally well is take the already-upgraded concentrate a Knelson, Falcon, or spiral produces, a small fraction of the original feed volume, and clean it further into a genuinely high-grade product ready for smelting or final leaching.
This staged approach, high-throughput primary recovery followed by low-throughput, high-selectivity cleaning, mirrors the same logic used throughout mineral processing generally: each stage is matched to the volume and grade of material it actually needs to handle rather than a single piece of equipment being asked to do everything. Asking a table to process raw feed directly would waste its precision on a task better suited to cheaper, higher-capacity equipment.
What does a table concentrate actually look like at the end of the process?
A finished table concentrate is a visibly gold-rich band, often containing enough free gold to be smelted directly or leached in a small, dedicated batch rather than passed through the plant's main leach circuit. That distinct visual banding is also a practical operator check: a table that is running correctly shows clean separation, while a poorly tuned one shows overlapping or smeared bands, an immediate sign that deck angle or wash water needs adjusting.
The middlings band, the intermediate zone between the clean concentrate and the gangue-dominated tailings, typically gets recirculated back through the table or through an earlier cleaning pass rather than being assigned outright to either product. Skilled table operation is largely about minimizing that middlings band, tuning deck angle, stroke, and wash water until the three-way split narrows to the cleanest possible concentrate and the leanest possible tailings with as little ambiguous material in between as achievable.
What types of shaking tables are used in gold recovery?
Wilfley-pattern tables are the most widely recognized deck design in gold gravity circuits, with a rectangular deck and a specific riffle pattern that has become something close to an industry standard reference point, similar to the way Knelson and Falcon anchor the centrifugal category. Other manufacturers produce variations on the same underlying principle, differing in deck material, drive mechanism, and riffle geometry, but the reciprocating-motion-plus-wash-water principle is common across the category. Deck size itself scales with the concentrate volume a project's primary gravity stage is expected to produce, since a table sized for a small-scale operation would simply overflow if fed the concentrate volume from a large, multi-unit centrifugal or spiral bank.
Duplex and multi-deck table configurations, running two or more decks on a shared drive frame, exist for operations needing more cleaning capacity than a single deck provides without the floor space a fully separate second table would require. These are less common on a typical tailings retreatment project than a single-deck table, but worth knowing as an option where a project's concentrate volume genuinely warrants it.
Where exactly does a table sit in a Ghanaian retreatment circuit?
A shaking table sits at the very end of the gravity concentration sequence, receiving concentrate from a Knelson, Falcon, or spiral stage and producing the final gravity gold product the plant will smelt or leach separately from the main tailings stream. Its tailings output, the material the wash water carries off the deck, is not waste in the same sense as final plant tailings; it typically still carries some middlings-grade material and is recirculated back into the primary gravity circuit rather than discarded, capturing value that would otherwise be lost.
On a Ghanaian retreatment project specifically, this final cleaning stage is also where a project's gravity gold recovery becomes a genuinely countable, bankable product rather than an estimate, since a clean table concentrate can be weighed, sampled, and assayed with a precision the earlier, higher-volume stages cannot match. That bankability matters directly to the investment case a project presents, since early, verifiable gravity gold production is often the first tangible proof point a retreatment operation can show before its full leach circuit comes online.
What operating factors affect table performance?
Table performance depends on deck angle, wash water rate, and feed density, and getting all three right takes more operator skill than the largely automated centrifugal units in the same circuit require. Too much wash water pushes valuable fine gold off with the gangue; too little leaves gangue mixed into the concentrate band. That sensitivity is the tradeoff for a table's excellent selectivity once it is properly tuned.
Stroke length and stroke frequency are two further variables an operator adjusts, typically through a mechanical or electronically controlled drive head, and both interact with deck angle and wash water rather than acting independently. A change to one variable generally requires re-checking the others, which is why experienced table operators develop an intuitive feel for a specific feed material over time rather than relying purely on a fixed factory setting sheet. Feed consistency again matters here: a table tuned for one concentrate composition performs noticeably worse if the upstream primary stage's output composition drifts significantly, which is one more reason consistent upstream feed preparation pays off throughout the whole gravity circuit, not only at the primary stage.
Do shaking tables have a role beyond cleaning duty?
Tables can serve as a primary recovery unit at genuinely small, artisanal scale, but that is not the typical role for a Ghanaian retreatment-scale project, where throughput requirements make a centrifugal or spiral primary stage the practical choice and reserve the table for cleaning duty afterward.
How this connects to the fine gold problem
A well-run table can recover gold fine enough to challenge primary gravity equipment, which is part of why it pairs so naturally with fine gold recovery: the sub-75-micron problem.
Why final concentrate handling matters for security and accountability
A table's finished concentrate is, gram for gram, the most valuable material anywhere in the plant, and its handling from table discharge through to smelting or sale needs the same rigor applied to any high-value inventory: controlled access, weighed and logged handoffs between shifts, and a clear chain of custody. Sound governance around this final handling step matters as much to a project's credibility with investors and regulators as the metallurgical performance of the equipment producing it.
Sampling the table concentrate for accurate grade reporting
Because the finished concentrate is such a small, high-value fraction of the original feed, representative sampling matters more here than almost anywhere else in the plant; a poorly taken sample can materially misstate the grade of a batch worth reporting to investors or regulators. Applying the same rigor described by Gy's sampling theory elsewhere on this site, taking multiple increments across the full batch rather than a single grab sample, is standard practice for any concentrate destined for an assay report that will inform a production or investment decision.